Traditional allergy tests can lead to misdiagnosis

Scientists found an over-reliance on traditional allergy tests can often lead to misdiagnosis

Doctors are being warned that blood tests and skin-prick
testing are not reliable ways of detecting allergies.

Scientists discovered an over-reliance on traditional allergy tests can lead to a misdiagnosis and ill-advised cautionary measures.

Clinicians are now being urged to interpret test results in the context of a patient's symptoms and medical history.

The number of people affected by allergies has trebled in the past 20 years and it is estimated that a third of the population will develop symptoms at some point in their lives.

But the latest study suggests that many patients are being wrongly diagnosed.

Lead researcher Robert Wood of the Johns Hopkins Children's Center in New York said: 'Allergy tests can help a clinician in making a diagnosis but tests by
themselves are not diagnostic magic bullets or foolproof predictors of
clinical disease.

'Many children with positive tests results do not have allergic
symptoms and some children with negative test results have allergies.'

Allergies occur when the body’s immune system reacts negatively to a particular food or substance, causing a wide range of physical symptoms, including skin reactions, digestive problems and hay-fever-like symptoms, such as sneezing.

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Undiagnosed allergies can be dangerous, and in some cases fatal.

The number of people admitted to hospital with life-threatening anaphylactic shock – involving sudden swelling, breathlessness and low blood pressure – has increased by around 700 per cent in the last two decades.

Anaphylaxis is a serious condition often triggered by allergies to things such as bee stings or peanuts.

The number of people with life-threatening anaphylactic shock has increased by around 700 per cent

Experts are now highlighting allergy tests should be used with caution to avoid misdiagnosis.

Skin testing involves pricking the skin with small amounts of an allergen to monitor how the skin reacts.

An irritated area of skin at the injection site signals that the patient's immune system has created antibodies to the allergen.

These
tests can tell whether someone is sensitive to a particular substance
but experts claim many who have positive skin tests or measurably elevated IgE
antibodies do not have allergies.

Past research has indicated that up to eight per cent of children have a
positive skin or blood test for peanut allergies, but only one per cent of
them have clinical symptoms.

Co-author Scott Sicherer of Mt. Sinai Hospital in New York, who detailed findings in the January issue of Pediatrics, said: 'Patients should not be told they are allergic based
solely on either a skin test or the identification of [allergen-specific
immunoglobulin].'

Food allergies affect around 8 per cent of children up to the age of three across Europe and North America.